dizertační práce

Terahertzová anténní pole pro komunikaci

Text práce 7.14 MB Teze 2.87 MB

Autor práce: Ing. Dominika Warmowska, MSc

Ak. rok: 2020/2021

Vedoucí: prof. Dr. Ing. Zbyněk Raida

Oponenti: prof. Miroslav Joler, Ing. Michal Pokorný, Ph.D.

Abstrakt:

The thesis is focused on the research of THz antenna arrays to be used for communications. Attention is turned to modeling metallic surfaces at THz frequencies, a proper characterization of gold conductivity, its relation to Drude model and corresponding measurements. Moreover, the best methods for modeling thin metallic layers (depending on the skin depth related to the metal thickness) are presented.
An optimized element of a THz 2×2 antenna array designed for the application of communications is developed in a way that enables an expansion to a larger array. The expansion ability is demonstrated on a 4×4 antenna array which is presented in the thesis too. The designed antennas achieve parameters better than the state-of-art antennas. The presented antennas radiate circularly polarized wave at THz frequencies, operate in a wide bandwidth, have a high gain and are of a compact size.
In the thesis, an 8×8 antenna array with a beam steering capability is presented. The main beam of the antenna array can be controlled in two dimensions. A high gain of the radiated circularly-polarized wave can be achieved that way.
Different approaches to modeling antennas with thin metallic layers are compared and the best methods are recommended from the viewpoint of different requirements. The designed 2×2 and 4×4 antenna arrays are manufactured using a microfabrication technology. Each step of the fabrication is described in detail and discussed. The reflection coefficient at the input of antennas is measured and compared with simulations. Discrepancies in results are associated with surface roughness which is analyzed by a scanning probe microscope and a scanning electron microscope.
By down-scaling the developed THz antenna, a low-profile high-gain antenna for Ka-band space applications is designed. The presented antenna achieves better results than state-of-art CubeSat antennas. The antenna performance is verified by a prototype to be operated at 9 GHz, and the radiation characteristics are experimentally confirmed.

Klíčová slova:

THz antenna arrays, microfabrication, micromachining, corporate-feed arrays, beam steering, high-gain antennas, circularly polarized antennas, antennas for space applications, thin metal modeling, THz antenna modeling, thin gold modeling.

Termín obhajoby

1.9.2020

Výsledek obhajoby

obhájeno (práce byla úspěšně obhájena)

znakmkaPznamka

Průběh obhajoby

Práce Ing. Dominiky Warmovské se zabývá vývojem antén pro komunikaci v terahertzových pásmech, porovnáním přístupů pro modelování metalických povrchů a zobecněním návrhových metod pro mikrovlnná pásma. Dizertační práce splňuje v důležitých aspektech stanovené cíle, přináší nové poznatky a metody v oblasti návrhu anténních polí . Doktorandka spojila ve své práci teoretické znalosti s technicko-inženýrskými schopnostmi a potvrdil tak svoji schopnost samostatné vědecké práce na velmi dobré úrovni. Komise se jednomyslně usnesla na závěru, že Ing. Dominika Warmovská splnila cíle dizertační práce a dosaženými výsledky a publikační činností splnila podmínky k udělení akademického titulu doktor.

Jazyk práce

angličtina

Fakulta

Ústav

Studijní program

Elektrotechnika a komunikační technologie (EKT-PP)

Studijní obor

Elektronika a sdělovací technika (PP-EST)

Složení komise

prof. Ing. Aleš Prokeš, Ph.D. (předseda)
doc. Ing. Libor Dražan, CSc. (člen)
doc. Ing. David Vrba, Ph.D. (člen)
doc. Ing. Václav Kotlan, Ph.D. (člen)
doc. Ing. Jaroslav Láčík, Ph.D. (člen)
prof. Miroslav Joler - oponent (člen)
Ing. Michal Pokorný, Ph.D. - oponent (člen)

Posudek vedoucího
prof. Dr. Ing. Zbyněk Raida

The dissertation thesis submitted by Dominika Warmowska is focused on modeling, design, manufacturing and measurement of terahertz antenna arrays. Developed design and characterization procedures were repeated at lower frequencies to show design specifics of different frequency bands.

In the thesis, several original ideas were presented. Personally, I appreciate:

- The study comparing different numerical approaches for the characterization of conductive surfaces at terahertz frequencies. Dominika used different solvers and different boundary conditions to formulate modeling recommendations as a trade-off between CPU-time demands and the accuracy.

- The general procedure to design circularly-polarized corporate-fed antenna arrays. The developed concept allows frequency scaling, is modular (larger arrays can be easily built), and provides beam-steering capability (when completed by phase shifter). Moreover, reasonable parameters of the arrays were achieved.

Obviously, the dissertation thesis is original in several aspects. This fact can be proven:

- By 4 records in Scopus including 1 journal article (IEEE Access) and 3 conference papers.

- By the active participation in the H2020 Innovative Training Network "Convergence of Electronics and Photonics Technologies for Enabling Terahertz Applications (CELTA)". Thanks to this network, Dominika completed parts of her research at TU Darmstadt, KTH Stockholm and Carlos III University Madrid. Dominika also participated in Summer Schools and other CELTA activities.

Dominika was also engaged in the education at the university:

- She supervised bachelor thesis focused on energy harvesting.

- She contributed to teaching and updating computer exercises in several courses oriented to applied electromagnetics.

Obviously, Dominika meets all usual requirements on a PhD candidate. I therefore fully recommend PhD thesis authored by Dominika to be defended.

Posudek oponenta
prof. Miroslav Joler

viz příloha pdf
Soubor vložený oponentem Velikost
Posudek oponenta [.pdf] 283.51 kB

viz příloha pdf
Soubor vložený oponentem Velikost
Posudek oponenta [.pdf] 747.74 kB